1. Technical Field
The present invention pertains to systems for heating medical items. In particular, the present invention pertains to a system for heating and maintaining medical solutions (e.g., bags or containers containing saline or intravenous (IV) solutions, antibiotics or other drugs, blood, etc.) at desired temperatures.
2. Discussion of Related Art
Various types of medical items require heating to a selected temperature prior to utilization in a medical procedure. In particular, medical items, such as intravenous (IV) fluid bags, are typically heated to precise temperatures to prevent thermal shock and injury from occurring during infusion of such IV fluid into a patient. In order to provide the necessary heated items for use in certain medical procedures, medical personnel typically utilize a warming system to heat items toward their operational temperatures.
The related art has provided several variations of warming systems for heating medical or other items to desired operational temperatures. For example, ovens may be disposed within operating rooms to heat items to desired temperatures. Further, U.S. Pat. No. 4,419,568 (Van Overloop) discloses a wet dressings heater having a base with side walls defining a cavity, and an insert connected to the base and defining at least one recess in the cavity for receiving wet dressings. A heater has an electrical heating element in close proximity to the insert recess for heating the wet dressings, while the temperature of the heating element is controlled in a desired temperature range for those wet dressings.
U.S. Pat. No. 4,495,402 (Burdick et al) discloses a warmer for heating wet dressings and other articles disposed within a heating and storage compartment. The articles are arranged within the compartment in stacked relation and disposed on a plate that is supplied with thermal energy from a heater. The plate includes a center aperture whereby a first thermal sensor is disposed in the aperture in contact with a bottommost article. Control circuitry is disposed beneath the plate to control the heater to maintain temperature of the bottommost article at a desired level based on the temperatures sensed by the first thermal sensor and a second thermal sensor responsive to heater temperature.
U.S. Pat. No. 5,408,576 (Bishop) discloses an intravenous fluid warmer having a cabinet structure to accommodate a plurality of intravenous fluid bags. A temperature sensor and pad of heating filaments are disposed within the cabinet structure, whereby the temperature sensor enables automatic temperature regulation of the pad of heating filaments to heat the intravenous fluid bags. The heating filaments are covered by a rubber layer to prevent melting of the bags during heating. A temperature indicator disposed on the cabinet structure permits a user to ascertain when a desired temperature is attained, whereby an intravenous fluid bag is removed from the intravenous fluid warmer via an opening defined in a side of the cabinet structure.
U.S. Pat. No. 5,986,239 (Corrigan, III et al.) discloses a conductive warmer for flexible plastic bags. The warmer includes a heat-conducting member of thermally conductive material having a plurality of fins which are parallel and spaced apart to define a plurality of bag-receiving compartments. The fins are connected to a back portion of the heat-conducting member to which a heating element is attached in a heat-exchanging relationship. The heating element conducts heat through the back portion and fins of the heat-conducting member to the bags.
The warming systems described above suffer from several disadvantages. In particular, ovens typically do not have a high degree of accuracy or control, thereby enabling use of items having temperatures incompatible with a medical procedure and possibly causing injury to a patient. Further, ovens or other warming systems employed in the operating room generally require a substantial time interval to heat items to desired temperatures. This either delays the medical procedure or requires the additional task or preheating the items well in advance of commencing the procedure. The Burdick et al and Bishop warmers employ heaters that generally contact a particular portion of an article being heated, thereby heating articles in an uneven manner and enabling formation of hot spots. Moreover, the Burdick et al, Bishop, Corrigan, III et al and Van Overloop warming systems employ a heating element covering a substantial portion of a conducting member, thereby increasing system costs and power usage. In addition, the above described systems do not control operation based on detection of the presence of items placed within the systems. This enables the systems to operate absent items placed therein, thereby needlessly consuming power and facilitating potential damage to system heating or other components.
Accordingly, it is an object of the present invention to rapidly heat a medical item to a desired temperature in preparation for use of that medical item in a medical procedure.
It is another object of the present invention to heat a medical item to a desired temperature by uniformly distributing heat about the medical item, thereby avoiding creation of xe2x80x9chot spotsxe2x80x9d and xe2x80x9ccold spotsxe2x80x9d.
Yet another object of the present invention is to directly measure a temperature of a medical item being heated to effectively control heating of the medical item to the desired temperature.
Still another object of the present invention is to automatically enable a heater in a warming system in response to the presence of the medical item within the warming system.
A further object of the present invention is to evenly distribute heat about a medical item within a warming system by conducting heat through a heating plate that at least partially surrounds the medical item.
Yet another object of the present invention is to facilitate loading of a plurality of medical items within a warming system housing for heating to desired temperatures prior to use in medical procedures.
The aforesaid objects may be achieved individually and/or in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
According to the present invention, a temperature controlled system includes a system housing with a compartment defined therein. The compartment includes a heating assembly with a generally xe2x80x98Uxe2x80x99-shaped heating plate and corresponding heater. The heating plate is configured to evenly distribute heat to a medical item (e.g., a medical solution container, etc.) placed thereon, while a limit switch facilitates control of power to the heater. The limit switch is typically positioned near a bearing surface of the heating plate to enable a limit switch arm to directly contact medical solution containers placed on the heating plate. The limit switch facilitates heater actuation in response to placement of a medical item on the heating plate. A temperature sensor measures the temperature of solutions disposed within the housing compartment, and is preferably positioned on the limit switch arm to directly contact a medical solution container. A system controller facilitates entry of desired temperatures and controls the heating assembly based on a comparison of the desired temperature with the temperature measured by the temperature sensor. The controller includes a display for indicating the solution temperature. In one embodiment of the present invention, the system housing includes a heating compartment for heating medical solution containers and a storage compartment for receiving and retaining medical solution containers prior to being heated within the heating compartment.
Thus, the present invention overcomes the aforementioned problems and provides several advantages. For example, the warming system of the present invention distributes heat evenly to one or more medical items of varying shapes and sizes, thereby ensuring rapid and relatively uniform heating and the elimination of potential xe2x80x9chot spotsxe2x80x9d or xe2x80x9ccold spotsxe2x80x9d for the items. Further, the warming system of the present invention provides a temperature sensor that directly measures the temperature of medical items disposed within the system, thereby providing an accurate temperature indication of those medical items and enhanced temperature control. Moreover, the present invention includes a switch to autonomously enable the heater in response to a medical item being disposed on the heating plate. This ensures that heating within the system only occurs when medical items are disposed on the heating plate so as to render the system energy efficient and promote longevity of the heating element.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of specific embodiments thereof, particularly when taken in conjunction with the accompanying drawings, wherein like reference numerals in the various figures are utilized to designate like components.